Testing the applicability of a virtual reality simulation platform for stress training of first responders

The current study explores whether different stressors in a virtual reality (VR) military training scenario cause increases in physiological stress. This would validate the use of VR simulation for stress training, as well as the physiological monitoring of trainees for educational purposes. Military cadets (n = 63) performed a patrol scenario ...

Heterogeneity and prediction of hemodynamic responses to dobutamine in patients with septic shock

OBJECTIVE: To establish the heterogeneity of hemodynamic responses to dobutamine in patients with septic shock and to identify the predictive factors of these hemodynamic responses. DESIGN: Prospective study. SETTING AND PATIENTS: A total of 12 patients with septic shock in a tertiary medical intensive care unit. INTERVENTIONS: A 20-min...

Sublingual nitroglycerin used in routine tilt testing provokes a cardiac output-mediated vasovagal response

Objectives We set out to determine the effect of sublingual nitroglycerin (NTG), as used during routine tilt testing in patients with unexplained syncope, on hemodynamic characteristics and baroreflex control of heart rate (HR) and systemic vascular resistance (SVR). Background Nitroglycerin is used in tilt testing to elicit a vasovagal response...

Thoracic sympathectomy: Effects on hemodynamics and baroreflex control

Endoscopic thoracic sympathectomy at T2-T4 is an effective and safe treatment for primary axillary and palmar hyperhidrosis and facial blushing refractory to conventional treatment. T2 and T4 ganglia however are in the direct pathway of sympathetic innervation of the heart and part of the vasomotor nerves. In this study we investigate possible...

A comparison of cardiac output derived from the arterial pressure wave against thermodilution in cardiac surgery patients

In three clinical centres, we compared a new method for measuring cardiac output with conventional thermodilution. The new method computes beat-to-beat cardiac output from radial artery pressure by simulating a three-element model of aortic input impedance, and includes non-linear aortic mechanical properties and a self-adapting systemic...

Left ventricular wall stress normalization in chronic pressure-overloaded heart: A mathematical model study

It is generally accepted that the left ventricle (LV) hypertrophies (LVH) to normalize systolic wall stress (σ(s)) in chronic pressure overload. However, LV filling pressure (P(v)) may be elevated as well, supporting the alternative hypothesis of end-diastolic wall stress (σ(d)) normalization in LVH. We used an LV time-varying elastance model...

Hemodynamic effects of intermittent manual lung heperinflation in patients with septic shock

OBJECTIVE: The purposes of this study were to investigate the hemodynamic changes induced by intermittent manual lung hyperinflation (MHI) and to assess if these changes are adverse enough to warrant prohibition of MHI as a routine procedure in the care of patients with septic shock. DESIGN: The study's design was experimental prospective....

Influence of inhibition of nitric oxide synthesis on cardiac function in the newborn lamb after hypoxic-ischemic injury

The aim of the present study was to investigate the effect of immediate post-hypoxic-ischemic (HI) inhibition of nitric oxide synthesis by N(ω)- nitro-L-arginine (NLA) on cardiac function and reactive oxygen species production. Fifteen newborn lambs were subjected to severe HI. Upon resuscitation 5 received 10 mg NLA/kg, 4 40 mg NLA/kg and 6 a...

Hyperoxia and local organ blood flow in the developing chick embryo

1. Hyperoxia can cause local vasoconstriction in adult animal organs as a protective mechanism against hyperoxia-induced toxicity. It is not known at what time during development this vasoconstrictor capacity is present. Therefore, we measured the cardiac output (GO) distribution in different organs during a period of acute hyperoxia (100% O2)...

Effects of arteriovenous fistulas on cardiac oxygen supply and demand

Background. Arteriovenous (AV) fistulas used for hemodialysis access may affect cardiac load by increasing the preload while decreasing the afterload. In dogs, AV fistulas have also been shown to affect coronary perfusion negatively. We investigated the net effect of AV fistulas on cardiac oxygen supply and demand. Methods. Aortic pressure waves...

Why use Finapres or Portapres rather than intra-arterial or intermittent non-invasive techniques of blood pressure measurement?

In the clinic, blood pressure is measured almost exclusively using non- invasive intermittent techniques, of which the auscultatory (Riva- Rocci/Korotkoff, RRK) and the computerized oscillometric method are most often used. However, both methods only provide a momentary value. In addition, the accuracy is hampered by phenomena such as cuff...

Variability of near-fainting responses in healthy 6-16-year-old subjects

1. Fainting is a common phenomenon in young subjects, but the final events before the actual faint are not well known. The aim of the present study was to study the inter-individual variability of haemodynamic events associated with near-fainting in children and teenagers. 2. Sixty-eight healthy subjects (aged 6-16 years) performed a 70°tilt-up...

Finger arterial versus intrabrachial pressure and continuous cardiac output during head-up tilt testing in healthy subjects

1. The aims of this study were to determine the clinical feasibility of continuous, non-invasive Finapres recordings as a replacement for intrabrachial pressure during a 30 min head-up tilt, and the reliability of continuous cardiac output computation by pulse contour analysis from the finger arterial versus the brachial waveform. 2. In eight...

Single injection thermodilution: A flow-corrected method

Application of the Stewart-Hamilton equation in the thermodilution technique requires flow to be constant. In patients in whom ventilation of the lungs is controlled, flow modulations may occur leading to large errors in the estimation of mean cardiac output. Methods: To eliminate these errors, a modified equation was developed. The resulting...

Computation of aortic flow from pressure in humans using a nonlinear, three-element model

We computed aortic flow pulsations from arterial pressure by simulating a nonlinear, time-varying three-element model of aortic input impedance. The model elements represent aortic characteristic impedance, arterial compliance, and systemic vascular resistance. Parameter values for the first two elements were computed from a published, age...

Cardiovascular instability and baroreflex activity in a patient with tetanus

In a patient with tetanus we tested the hypothesis that the hyperadrenergic cardiovascular instability might be due to impairment of the baroreceptor reflex by the tetanus toxin. Baroreflex sensitivity assessed with the phenylephrine method was found to be normal. Changes in arterial pressure correlated inversely with relative changes in plasma...

An adequate strategy for the thermodilution technique in patients during mechanical ventilation

The application of the thermodilution method in conditions associated with variations in blood flow implies a misuse of the Stewart Hamilton equation. Therefore, we studied the reliability of the thermodilution method for the estimation of mean cardiac output (CO) during mechanical ventilation in patients (n = 9). Variation of the injection...